Structures were above water about 9,000 years ago
The Ann Arbor News: Using detailed government data on lake floor topography, a research vessel and a remote mini-rover equipped with a camera, scientists found what they believe are hunting pits, camps and rock structures called caribou 'drive lines' on the bottom of Lake Huron. Drive lines, also called drive lanes, are walls built of rocks that hunters used to lure caribou into ambush. A peculiarity of the deer species is that it readily follows linear cues, even though the rock walls are short enough to step over.
The structures were found on an underwater ridge that -- about 9,000 years ago --- was a land bridge above water. The 10-mile-wide Alpena-Amberly ridge stretches more than 100 miles from near Point Clark, Ontario to Presque Isle. The 1,148-foot 'drive line' structure found by U-M researchers closely resembles one previously discovered on Victoria Island in the Canadian subarctic.
'This is a really important time period in human history in North America,' said John O'Shea, curator of Great Lakes Archaeology in the U-M Museum of Anthropology... Much land-based archaeological evidence about early North Americans has been lost to time. But the extreme cold and neutral fresh waters of the Great Lakes help to preserve such finds.
Science Daily: The Paleo-Indians were nomadic and pursued big game, O'Shea said. With the Archaic period, communities were more settled, with larger populations, a broad spectrum economy, and new long distance trade and ceremonial connections. 'Without the archaeological sites from this intermediate time period, you can't tell how the got from point A to point B, or Paleo-Indian to Archaic. This is why the discovery of sites preserved beneath the lakes is so significant.'
Perhaps more exciting than the hunting structures themselves is the hope they bring that intact settlements are preserved on the lake bottom. These settlement could contain organic artifacts that deteriorate in drier, acidic soils on land.